Enable switching of HLU layers - common (CR31)

Enable the user to switch between different HLU layers, where there is
more than one valid layer in the current document/workspace.  This
commit contains the common (ArcGIS/MapInfo independent) files only.
Enable switching of HLU layers - MapInfo (CR31)

Enable the user to switch between different HLU layers, where there is
more than one valid layer in the current document/workspace.  This
commit contains the MapInfo files only.
Changes to version number and readme files

Change the version number in the assembly and installer and in the
readme files.